This invention is directed to a safety device for arresting the falling motion of a cage or skip in a mine shaft environment. It is more specifically directed to an opposing cam-type safety brake which is used in conjunction with tubing guides for stopping the sudden free fall motion of the cage or skip conveyance.
In the past it has been common to apply various types of safety brake devices to conveyances which have been utilized in mine shafts for many years. In some of those cases, the brake or arrester devices have utilized cutting teeth for use with wood guides.
In one known case a gear rack is provided longitudinally in the mine shaft in which the hoist cage operates. A pair of gears extending on shafts through each side of the cage engages with the rack and provides a braking device on the gear shaft so that if the hoisting cable should break or other malfunction occur the braking device on the shaft would immediately seize arresting any falling motion of the hoist cage.
In another instance it has been known to arrange outwardly settable pins in conjunction with the hoist cage so that if the hoist cable should break the pins would automatically engage openings or slots in stationary rails on the side of the shaft so that the cage will be locked in place automatically. Other types of arresting devices provide clamping blocks which have a high friction material on the surface of the blocks so that the blocks will move outwardly against a stationary surface such as the walls of the shaft or safety guides provided vertically along the sides of the shaft.
Still other safety arrangements provide additional safety cables and support devices to attempt to arrest and control any sudden downward or falling motion of the cage in order to protect and save any passengers or equipment which may be inside.
The safety devices which have been described above are rather rudimentary and crude with respect to safely arresting the falling motion of a mine passenger cage. In many mine situations these devices cause a sudden, violent stopping motion which when used in conjunction with human passengers can cause considerable injury to these passengers. The primary consideration in a mine shaft environment has been the arresting or sudden stopping of the falling motion of the cage with little regard given to the actual welfare of the passengers as well as the surrounding structure or those persons who may be in the vicinity of the falling cage. Due to the weight of the cage which is used in mine shafts not only for the movement of passengers but also freight and products of the mining operation, the cage must be extremely strong and heavy. This necessitates a rather bulky structural integrity with little regard for the comfort or protection of human passengers. Thus, a high gravitational pull could be applied to the human passengers upon the actuation of the arresting devices which have been utilized in the past.
To overcome these problems and yet safely stop the falling motion of a passenger cage, it is an object of the present invention to provide an absolute foolproof device which can smoothly decelerate and safely stop the falling motion of a passenger cage without causing injury to the passengers.
It is a still further object of the present invention to provide a mine shaft passenger safety arrester which can positively stop the falling motion of the cage under and adverse environmental condition which can be experienced in a mine shaft operation.
It is a further object of the present invention to provide a safety arrester for a mine shaft passenger cage in which the arrester will absolutely stop the falling motion of the cage in a relatively progressive operation which will provide only a reasonable deacceleration force to the passengers to prevent injury.
It is another object of the present invention to provide an arresting device for mine shaft passenger cage which utilize a pair of tube guides in controlling the horizontal motion of the cage and where the arresting device will constantly adjust the configuration of its contact surface to the deformation of the stationary tube guides to provide a constant, controlled deacceleration.
It is a tertiary object of the present invention to provide a mine passenger cage safety arrester which is relatively simple and reasonable in cost and yet fully reliable in operation.